This is a note to let you know that I've just added the patch titled
ALSA: msnd: Optimize / harden DSP and MIDI loops
to the 3.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
alsa-msnd-optimize-harden-dsp-and-midi-loops.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 20e2b791796bd68816fa115f12be5320de2b8021 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@xxxxxxx>
Date: Thu, 6 Jul 2017 12:34:40 +0200
Subject: ALSA: msnd: Optimize / harden DSP and MIDI loops
From: Takashi Iwai <tiwai@xxxxxxx>
commit 20e2b791796bd68816fa115f12be5320de2b8021 upstream.
The ISA msnd drivers have loops fetching the ring-buffer head, tail
and size values inside the loops. Such codes are inefficient and
fragile.
This patch optimizes it, and also adds the sanity check to avoid the
endless loops.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=196131
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=196133
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: grygorii tertychnyi <gtertych@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
sound/isa/msnd/msnd_midi.c | 28 ++++++++++++++--------------
sound/isa/msnd/msnd_pinnacle.c | 23 ++++++++++++-----------
2 files changed, 26 insertions(+), 25 deletions(-)
--- a/sound/isa/msnd/msnd_midi.c
+++ b/sound/isa/msnd/msnd_midi.c
@@ -120,24 +120,24 @@ void snd_msndmidi_input_read(void *mpuv)
unsigned long flags;
struct snd_msndmidi *mpu = mpuv;
void *pwMIDQData = mpu->dev->mappedbase + MIDQ_DATA_BUFF;
+ u16 head, tail, size;
spin_lock_irqsave(&mpu->input_lock, flags);
- while (readw(mpu->dev->MIDQ + JQS_wTail) !=
- readw(mpu->dev->MIDQ + JQS_wHead)) {
- u16 wTmp, val;
- val = readw(pwMIDQData + 2 * readw(mpu->dev->MIDQ + JQS_wHead));
+ head = readw(mpu->dev->MIDQ + JQS_wHead);
+ tail = readw(mpu->dev->MIDQ + JQS_wTail);
+ size = readw(mpu->dev->MIDQ + JQS_wSize);
+ if (head > size || tail > size)
+ goto out;
+ while (head != tail) {
+ unsigned char val = readw(pwMIDQData + 2 * head);
- if (test_bit(MSNDMIDI_MODE_BIT_INPUT_TRIGGER,
- &mpu->mode))
- snd_rawmidi_receive(mpu->substream_input,
- (unsigned char *)&val, 1);
-
- wTmp = readw(mpu->dev->MIDQ + JQS_wHead) + 1;
- if (wTmp > readw(mpu->dev->MIDQ + JQS_wSize))
- writew(0, mpu->dev->MIDQ + JQS_wHead);
- else
- writew(wTmp, mpu->dev->MIDQ + JQS_wHead);
+ if (test_bit(MSNDMIDI_MODE_BIT_INPUT_TRIGGER, &mpu->mode))
+ snd_rawmidi_receive(mpu->substream_input, &val, 1);
+ if (++head > size)
+ head = 0;
+ writew(head, mpu->dev->MIDQ + JQS_wHead);
}
+ out:
spin_unlock_irqrestore(&mpu->input_lock, flags);
}
EXPORT_SYMBOL(snd_msndmidi_input_read);
--- a/sound/isa/msnd/msnd_pinnacle.c
+++ b/sound/isa/msnd/msnd_pinnacle.c
@@ -170,23 +170,24 @@ static irqreturn_t snd_msnd_interrupt(in
{
struct snd_msnd *chip = dev_id;
void *pwDSPQData = chip->mappedbase + DSPQ_DATA_BUFF;
+ u16 head, tail, size;
/* Send ack to DSP */
/* inb(chip->io + HP_RXL); */
/* Evaluate queued DSP messages */
- while (readw(chip->DSPQ + JQS_wTail) != readw(chip->DSPQ + JQS_wHead)) {
- u16 wTmp;
-
- snd_msnd_eval_dsp_msg(chip,
- readw(pwDSPQData + 2 * readw(chip->DSPQ + JQS_wHead)));
-
- wTmp = readw(chip->DSPQ + JQS_wHead) + 1;
- if (wTmp > readw(chip->DSPQ + JQS_wSize))
- writew(0, chip->DSPQ + JQS_wHead);
- else
- writew(wTmp, chip->DSPQ + JQS_wHead);
+ head = readw(chip->DSPQ + JQS_wHead);
+ tail = readw(chip->DSPQ + JQS_wTail);
+ size = readw(chip->DSPQ + JQS_wSize);
+ if (head > size || tail > size)
+ goto out;
+ while (head != tail) {
+ snd_msnd_eval_dsp_msg(chip, readw(pwDSPQData + 2 * head));
+ if (++head > size)
+ head = 0;
+ writew(head, chip->DSPQ + JQS_wHead);
}
+ out:
/* Send ack to DSP */
inb(chip->io + HP_RXL);
return IRQ_HANDLED;
Patches currently in stable-queue which might be from tiwai@xxxxxxx are
queue-3.18/alsa-msnd-optimize-harden-dsp-and-midi-loops.patch